# Science at Home

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physics

## Sound Sandwich

Musicians manipulate the vibration that instruments create to make different notes or pitches. Try making this simple instrument to explore the physics of sound.

## Materials

• Two jumbo craft sticks
• One wide rubber band (#64 if you have them!)
• Two smaller rubber bands
• Straw
• Scissors

## Directions

1. Place a wide rubber band lengthwise over one craft stick.
2. Cut two pieces of straw that measure about 1 inch each.
3. Tuck two straw pieces underneath the rubber band and slide each straw to the opposite end of the craft stick, about 1 inch from the end.
4. Place another craft stick on top of the straws, like the top piece of bread on a sandwich.
5. Wrap a smaller rubber band around both of the craft sticks on one end of the sandwich to hold it together. Use another rubber band to do the same on the other end. The rubber bands should pinch the two craft sticks together, and there should be a small space between the two craft sticks created by the two pieces of straw.
6. Hold the sound sandwich up to your mouth and blow through the space between the sticks.

## What's happening?

When you blow through the sound sandwich, can you feel it vibrating against your lips? You just felt sound! Sound is produced when a vibration is transmitted through a solid, liquid or gas. When you blew air through the space between the craft sticks, that air caused the rubber band to vibrate (move up and down quickly) between the two craft sticks. The vibration produces a sound.

Sound moves just like the rubber band, up and down in a wave. Sound waves can have different lengths, and different wavelengths result in different sounds. When the straws are placed closer together, the part of the rubber band that vibrates is shortened and moves more quickly, resulting in a higher pitched sound.